Chemical composition of propolis depends on the specificity of the local flora at the site of collection and thus on the geographic and climatic characteristics of this place. This paper describes a comparative analysis of Cuban red propolis (CRP), Brazilian red propolis (BRP), and Dalbergia ecastophyllum exudates (DEE) by high-performance liquid chromatography with diode-array detection and tandem mass spectrometry. The aim of this study was to investigate the overall chemical profile and the botanical origin of red propolis and to suggest similarities and differences between samples collected in different tropical regions. Isoliquiritigenin (1), liquiritigenin and naringenin (2 and 17), isoflavones (3-4 and 16), isoflavans (5-7 and 18), and pterocarpans (8-13) were detected in CRP, BRP, and DEE, whereas polyisoprenylated benzophenones (PPBs) guttiferone E/xanthochymol (14a,b) and oblongifolin A (15) were detected only in BRP. Pigments responsible for the red color of DEE and red propolis were also identified as two C30 isoflavans, the new retusapurpurin B (19) and retusapurpurin A (20). PPBs and pigments were isolated and unambiguously characterized by 1D and 2D NMR analysis. These results show that red propolis samples from different tropical zones have a similar chemical composition. DEE is the main red propolis source, but the presence of PPBs in BRP suggests the contribution of different botanical sources for Brazilian samples. This chemical information is important for quality control of red propolis and its commercial products and for biological study.

Chemical investigation of a red-type Mexican propolis sample has led to the isolation of three new compounds, 1-(3',4'-dihydroxy-2'-methoxyphenyl)-3-(phenyl)propane (1), (Z)-1-(2'-methoxy-4',5'-dihydroxyphenyl)-2-(3-phenyl)propene (2) and 3-hydroxy-5,6-dimethoxyflavan (3), together with seven known flavanones, isoflavans, and pterocarpans. Structural determination, was accomplished by spectroscopic analysis, particularly 2D NMR and ESI-MS/MS techniques. The present study appears to be the first report on the occurrence of isoflavonoids in Mexican propolis. In addition, the presence of compounds with a 1,3-diarylpropane and 1,3-diarylpropene carbon skeleton were found for the first time in propolis. Isolated compounds 1-10 indicated the possible relation between red Mexican propolis and the genus Dalbergia.

No abstract

Chemical investigation of a propolis sample collected in Honduras has led to the isolation of the new (E,Z)-cinnamyl cinnamate (2) together with 14 known compounds: 6 cinnamic ester derivatives, 2 flavanones, 1 chalcone, 2 triterpenes, and 3 aromatic acids. Structural determination was accomplished by spectroscopic analysis, particularly two-dimensional (2D) nuclear magnetic resonance (NMR) and electrospray ionization-tandem mass spectrometry (ESI-MS/MS) techniques. Futhermore, we checked the ability of the propolis extract and the most representative compounds of each class (1, 5, 8, and 10) to inhibit the activity of Pdr5p, a protein responsible for a multidrug resistance phenotype in yeast. The present study appears to be the first report on Honduras propolis. Isolated cinnamic ester derivatives indicated the possible relation between Honduras propolis and the genus Liquidambar .

No abstract

Multidrug resistance of cancer cells and pathogenic microorganisms leading to the treatment failure of some forms of cancer or life-threatening bacterial or fungal infections is often caused by the overexpression of multidrug efflux pumps belonging to the ATP-binding cassette transporters superfamily. The multidrug resistance of fungal cells often involves the overexpression of efflux pumps belonging to the pleiotropic drug resistance (PDR) family of ABC transporters. Possibly the best-studied fungal PDR transporter is the multidrug resistance transporter Pdr5p of Saccharomyces cerevisiae. Some research groups have been searching for new inhibitors of these efflux pumps in order to alleviate resistance. Natural products are a great source for the discovery of new compounds with biological activity. Propolis is a complex resinous material collected by honeybees from exudates and buds of certain plant sources and this material is thought to serve as a defense substance for bee hives. Propolis is widely used in traditional medicine and is reported to have a broad spectrum of pharmacological properties. Literature reported some biological functionalities of propolis, such as antibacterial, antiviral, fungicidal, antiinflammatory and anti-carcinogenic activities. The chemical composition of propolis is qualitatively and quantitatively variable. Components isolated from methanolic extract of red Brazilian propolis (Alagoas, Northeast of Brazil) are isoflavonoids (including pterocarpans, isoflavans, isoflavones), flavanones and polyprenylated benzophenones. In this work we demonstrated the effects of five different isolated compounds on the ATPase activity of Pdr5p. Out of all five substances tested, only BRP-1 was able to completely abolish the enzymatic activity while others worked as positive modulators of the enzyme activity. BRP-1also inhibited the efflux of Rhodamine 6G from yeast cells overexpressing Pdr5p. Taken together, these results demonstrate that Brazilian propolis could be a source of promising compounds that can alleviate the MDR phenomenon, particularly in some fungi, where it could be used as an adjuvant for the treatment with azoles.

No abstract

No abstract